大跨混凝土箱梁桥温度荷载作用下剪力滞效应分析

Shear Lag Effect of Long-span Concrete Box Girder Bridge under Thermal Action

混凝土箱梁以其良好的结构整体受力性能在现代大跨桥梁结构中得到广泛的应用,但迄今所修建的混凝土箱梁桥中,在施工阶段或在运营阶段,箱梁上均存在较多的由温度引起的开裂现象,造成这一现象的主要原因是现有计算方法的不完善,其中之一就是未考虑箱梁在温度荷载作用下的剪力滞效应。本文采用有限元法对大跨混凝土箱梁桥在温度荷载作用及自重作用下的剪力滞效应进行了详细的分析,其结果表明在温度作用下,箱梁翼板底面存在着较为严重的剪力滞现象,并获得了箱梁在温度荷载作用下剪力滞效应的一般规律和初步结论,为箱梁的温度应力计算提供了参考。

The application of concrete box girder for long - span bridge has increased at present due to the advantage of structure behavior. However the cracks in the web still exist in many prestressed concrete bridges under thermal action during construction or service stage due to the ignorance of the shear lag effect of box girder. Based on FEM, a detail analysis on the shear lag effect of long - span concrete box girder bridge under thermal action is conducted in this paper. It is found that the shear lag effect of the bottom surface of the flange slabs under thermal action is obvious. And some conclusions are made which provide design consults for box girder determined under thermal action.